KR20090054583A - Apparatus and method for providing stereo effect in portable terminal - Google Patents

Abstract

An apparatus and a method for providing stereo effect in a portable terminal are provided to control the stereo effect according to the taste of a user by controlling a gain with regard to the phase difference of the components. An audio device includes a frequency converter(201), a frequency phase measuring unit(203), a component extractor(205), a gain controller(207) and a speaker(209). The component extractor extracts the mono components and the stereo component included in an audio signal. The gain controller calculates a signal ratio of a stereo component about the mono component and controls the stereo gain according to the signal ratio. The gain controller controls the stereo effect by controlling the stereo gain in an earphone output mode. The gain controller controls the stereo effect by controlling the stereo gain after applying a HRTF(Head Related Transfer Function) in an speaker output mode.

Description

Apparatus and method for providing stereo effect in portable terminal {APPARATUS AND METHOD FOR PROVIDING STEREO EFFECT IN PORTABLE TERMINAL}

The present invention relates to an audio device of a portable terminal, and more particularly, to an apparatus and method for providing a stereo effect when playing an audio file in a portable terminal.

Recently, portable terminals are indispensable for modern people regardless of gender, age and age, and service providers and terminal manufacturers are competitively developing products (or services) to differentiate themselves from other companies.

For example, the portable terminal may be a phone book, a game, a short message, an e-mail, a morning call, a digital camera, and a multimedia device capable of wireless internet service. Evolved to provide various additional functions.

Recently, according to the multimedia trend of the portable terminal, a portable terminal capable of playing music files has been developed and released. In other words, the portable terminal capable of reproducing music files as described above allows the user to listen to music using only the portable terminal without a conventional MP3 player or portable cassette.

Also, recently, an equalizer that adjusts specific frequencies of low, mid, and high ranges according to the genre of music played (rock, classic, ballad, jazz, dance, etc.) to provide music for the user's taste. Handheld devices are also available that offer stereo audio file playback and stereo audio file playback.

The stereo audio file reproduction function uses two signals, the "L" component and the "R" component, which are stereo components, as input signals, and adds the "L" component and the "R" component to increase the stereo effect. By outputting each of the "L" component, "R" component as an output signal, a method of enhancing the stereo effect, and using the two signals as the input signal of the "L" component and "R" component, By using the Head Related Transfer Function (HRTF) for each "L" component and "R" component, there is a method of increasing stereo effect by outputting at an appropriate angle.

A signal obtained by using two signals, the "L" component and the "R" component, which are the stereo components, as the sum of the "L" component and the "R" component, and each of the "L" component and the "R" component. By outputting the signal as an output signal, the method of enhancing the stereo effect has the advantage of being easy to implement due to the small amount of calculation since the head transfer function is not used. It has the disadvantage of not providing excellent performance because it is not considered for the head and the wheel.

In addition, the "L signal" may be included in the "L signal" and the "R signal" may be included in the "L signal" and the "R signal". There is a problem that "L component" may be included so that the stereo effect can be reduced.

Another method, the stereo component "L" component and "R" component using two signals as input signals, and using the head transfer function for each of the "L" component and "R" component at an appropriate angle The output method processes only the distinction between the "L signal" and the "R signal", and simultaneously processes the mono components included in both the "L signal" and the "R signal", thereby reducing the stereo effect. have.

The present invention was derived to solve the above problems, and an object of the present invention is to provide an apparatus and method for providing a stereo effect in a portable terminal.

Another object of the present invention is to provide an apparatus and method for extracting components of an input signal in order to provide stereo effects in a portable terminal.

Another object of the present invention is to provide an apparatus and method for adjusting a gain corresponding to a phase difference of each component in order to provide a stereo effect in a portable terminal.

According to a first aspect of the present invention for achieving the above objects, an audio device for providing a stereo effect in a portable terminal comprises a component extractor for extracting a mono component and a stereo component included in an audio signal, Comprising a signal ratio of the stereo component for, and adjusts the stereo gain according to the signal ratio, characterized in that it comprises a gain control unit.

According to a second aspect of the present invention for achieving the above objects, a method for providing a stereo effect in a portable terminal comprises the steps of extracting a mono component and a stereo component included in the audio signal, and a stereo component for the mono component The audio signal is output by adjusting the stereo effect through the step of calculating the signal ratio of the signal and adjusting the stereo gain according to the signal ratio.

As described above, the present invention extracts each component included in the input signal in the audio device of the portable terminal, and then adjusts the gain for the phase difference of the components to provide a stereo effect, thereby generating stereo in a conventional portable terminal. The problem of deterioration can be solved. In addition, the stereo effect can be adjusted according to the user's taste, and by using a simple frequency conversion scheme, the operation of the filter can be reduced compared to the prior art that provides a stereo effect by the operation of the filter.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In the following description, an apparatus and method for providing stereo effects in a portable terminal will be described. The portable terminal includes a cellular phone, a personal communication system (PCS), a personal data assistant (PDA), an international mobile telecommunication-2000 (IMT-2000), and a fourth generation broadband system ( It is meant to include both a mobile communication terminal capable of playing music, such as a broadband system, and a portable device such as an MP3 player and a portable multimedia player (PMP). The following description will be given with a general configuration of the above examples.

1 is a diagram illustrating an operation process of an audio device applied to a portable terminal according to an exemplary embodiment of the present invention.

Referring to FIG. 1, an operation process of the audio device virtually illustrates a process of generating a stereo signal, outputting it through the speaker 111 after encoding / decoding it.

First, it will be described assuming that two microphones 107 of the audio device receive channels (L signal, R signal) of both files of the stereo audio file. Accordingly, the "L signal" of the stereo audio file includes a mono component and an L component, and the "R signal" includes a mono component and an R component. In other words, the mono component is an “L signal”. Common in the "R signal", the "L component" and "R component" is present only in each signal.

At this time, the size of the components included in each signal is determined according to the phase difference for each frequency. In other words, as the stereo component is shifted to the left or the right, the phase difference is increased.

As shown in FIG. 1, when the "signal 1" 101 is positioned at the center of the left and right virtual microphones 107, the phases are the same in the virtual dotted line in the center. Accordingly, in order to extract the mono component from the "signal 1" 101, it is necessary to adjust the gain 1 to be the maximum adjustable.

In addition, in the case of the "signal 2" 103, since the signal is shifted to the left based on the "signal 1" 101, a phase difference occurs, so that some gain must be adjusted to extract the mono component. At this time, the gain adjustment range to be adjusted is 1> G> 0.

In addition, in the case of the "signal 3" 105, the phase difference is ∞ in a situation in which it is input only to the left virtual microphone 107 and not to the right virtual microphone. Accordingly, when the mono component is extracted, gain control should not be performed.

FIG. 1 conceptually illustrates a gain adjusting process for providing a stereo effect in the portable terminal, and a method for providing a stereo effect in the portable terminal will be described in detail later with reference to FIG. 4.

2 is a block diagram illustrating a configuration of an audio device applied to a portable terminal according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the audio device includes a frequency converter 201, a phase measuring unit 203 for each frequency, a component extracting unit 205, a gain adjusting unit 207, and a speaker 209. can do.

First, when an audio file decoding event occurs, the frequency converter 201 of the audio device performs a frequency conversion process of performing a Fast Fourier Transform (FFT) process on an input signal, and performs the frequency conversion. The signal from which the process is performed is provided to the phase measuring unit 203 for each frequency.

The phase-specific phase measuring unit 203 calculates phase information and phase magnitude of the signal on which the frequency conversion process is performed to calculate a gain according to a phase difference between a mono component and a stereo component, and calculates the phase difference for each frequency. And a value for distinguishing between the mono component and the stereo component using the phase difference.

The component extractor 205 extracts a component of an input signal using the gain and phase information for each frequency. That is, the component extractor 205 extracts a stereo component (R component and L component) and a mono component from the input signal.

The gain adjusting unit 207 calculates a signal ratio of the stereo component to the extracted mono component and adjusts the gain of the stereo component under optimum conditions. In this case, the gain adjusting unit 207 may adjust the gain according to the selection mode of the portable terminal or adjust the component ratio of a predefined stereo component. For example, the gain adjusting unit 207 may be adjusted to a level of 3dB to 9dB according to the taste of the user of the portable terminal or to an optimal stereo component ratio (6dB) confirmed through experiments.

The role of the audio device may be performed by the controller of the portable terminal. However, the configuration of the audio device separately illustrated in the present invention is an exemplary configuration for convenience of description and is not intended to limit the scope of the present invention. It will be appreciated that various modifications are possible within the scope of the invention. For example, the controller may be configured to process all of them.

3 is a flowchart illustrating a process for providing a stereo effect in a portable terminal according to the present invention.

Referring to FIG. 3, the portable terminal first determines whether an audio file decoding event occurs in step 301. If it is determined that the audio file decoding event does not occur, the portable terminal proceeds to step 311 to perform a corresponding function (eg, standby mode).

On the other hand, when it is determined that the audio file decoding event occurs, the portable terminal proceeds to step 303 to extract a mono component for the input signal, and proceeds to step 305 to extract a stereo component for the input signal.

Thereafter, the portable terminal adjusts the gains for the mono component and the stereo component extracted in steps 303 and 305, and then proceeds to step 309 to synthesize and output the mono component and the stereo component. Here, the gain for the mono component and the stereo component is a value for distinguishing the mono component and the stereo component, and may be used as a gain value for the phase difference of the components.

The portable terminal then terminates this algorithm.

4 is a flowchart illustrating a process of providing a stereo effect in a portable terminal according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the portable terminal determines whether an audio file decoding event occurs in step 401. If the audio file decoding event does not occur, the portable terminal proceeds to step 421 to perform a corresponding function (eg, standby mode).

On the other hand, when the audio file decoding event occurs, the portable terminal proceeds to step 403 to perform a frequency conversion process for the input signal, and proceeds to step 405 to the phase information and phase of the signal performing the frequency conversion process Calculate the size. Herein, the portable terminal performs the above process to calculate the gain according to the phase difference between each signal, that is, the mono component and the steer component.

In addition, the portable terminal may perform a frequency conversion process on the input signal by using a fast Fourier transform (FFT) equation as shown in Equation 1 below.

Here, x _i (n) represents the sample value of the input signal in the time domain of the i-th microphone, and X _i (k; m) represents the frequency domain transformed value. In addition, M is a frame size, and k and m represent a k th FFT point value and an m th frame, respectively.

A portable terminal performing a frequency process on an input signal by using the above method calculates phase information of the signal on which the frequency conversion process is performed by using Equation 2 below. By using the phase information, it is possible to calculate the phase magnitude of the signal subjected to the frequency conversion process.

Here, X (k; m) means a value that performs the frequency conversion process.

In step 407, the portable terminal calculates a phase difference for each frequency and a gain using the phase difference. Here, the gain using the phase difference refers to a value for distinguishing the mono component from the stereo component.

Here, the process of calculating the phase difference for each frequency of the portable terminal will be described using Equation 4 below.

As shown in Equation 4, the portable terminal calculates a phase difference for each frequency, and then calculates a gain for distinguishing the mono component and the stereo component using the following equation. That is, Equation 5 below is a formula for obtaining a gain value for the mono component, and Equation 6 below is a formula for obtaining a gain value for a stereo component.

Here, α is a constant for adjusting the amount of change of application according to the phase difference.

Here, α is a constant for adjusting the amount of change of application according to the phase difference.

In step 409, the portable terminal extracts components of the input signal using frequency-specific gain and phase information. That is, step 409 is a process of extracting the stereo component (R component and L component) and the mono component from the input signal, the portable terminal can extract the component of the input signal using the following equation. Of the equations to be described below, Equations 7 and 8 are equations for extracting stereo components, and Equations 9 are equations for extracting mono components.

Here, the G _stereo (k; m) represents the gain of the stereo component, the _{| X R (k; m)} | is "R" phase component size, the ∠X _R (k; m) is The phase information of the "R" component is shown.

Here, G _stereo (k; m) represents a gain value for a stereo component, and | X _L (k; m) | is a phase size of the "L" component, and ∠X _L (k; m) is The phase information of the "L" component is shown.

Here, the G _mono (k; m) represents the gain of the mono components, the _{| X L (k; m)} | is "L / R" phase component size, the ∠X _L (k; m ) Represents phase information of the "L / R" component.

In step 411, the portable terminal calculates the signal ratio of the stereo component to the mono component extracted in step 409, and proceeds to step 413 to adjust the gain of the stereo component under optimum conditions.

Herein, the portable terminal can calculate the signal ratio of the stereo component to the mono component using Equations 10 and 11 below.

Equation 10 is a formula for calculating a signal ratio of an "R" component to a mono component, wherein X _R (k; m) represents an "R" component extracted from an input signal, and X _mono (k; m ) Represents the mono component extracted from the input signal.

<Equation 11> is a formula for calculating the signal ratio of the "L" component to the mono component, wherein X _L (k; m) represents the "L" component extracted from the input signal, the X _mono (k; m) represents the mono component extracted from the input signal.

In addition, the portable terminal may adjust the gain according to the user's selection mode of the portable terminal or a component ratio of a predefined stereo component. For example, the portable terminal may be adjusted to a level of 3 dB to 9 dB according to a user's taste of the portable terminal or to an optimal stereo component ratio (6 dB) confirmed through experiments.

In step 415, the portable terminal checks the output mode of the portable terminal. If it is determined that the output mode of the portable terminal is the earphone output mode, the portable terminal proceeds to step 419 and synthesizes the stereo component and the mono component which have performed the gain adjustment in order to process to adjust the stereo effect by the stereo gain adjustment. Do it. In other words, the portable terminal processes and outputs the "L" component and the "R" component which performed gain adjustment by synthesizing with a mono component ("L" component + mono component, "R" component + mono component).

On the other hand, if it is determined that the output mode of the portable terminal is the speaker output mode, the portable terminal proceeds to step 417 as a filter coefficient modeling the path transmitted from the sound source to the ear drum, according to the relative positional relationship between the sound source and the head After applying the Head Related Transfer Function (HRTF) having the property that the value is different, proceed to step 419 and perform the gain adjustment to adjust the stereo effect by adjusting the stereo gain. And to synthesize the mono component. In other words, the portable terminal processes and outputs the "L" component and the "R" component which performed gain adjustment by synthesizing with a mono component ("L" component + mono component, "R" component + mono component).

The portable terminal then terminates this algorithm.

5 illustrates components extracted from an input signal according to an exemplary embodiment of the present invention. In the following description, FIG. 6 is a diagram illustrating an audio signal processing of components extracted from the audio device.

5 (a) is a diagram illustrating a stereo signal of the audio device according to the present invention.

Referring to FIG. 5A, the stereo signal includes an "L signal" and an "R signal". The "L signal" and "R signal" are composed of a mono component existing in common in the "L component", "R component" and the "L signal" and "R signal".

5 (b) is a diagram illustrating a mono component extracted by an audio device according to the present invention, and FIGS. 5 (c) and 5 (d) show an "L component" extracted from the "L signal" and "R signal". And "R component". When the above components are processed using the audio signal, the processing result as shown in FIG. 6 can be obtained.

Referring to Fig. 6 (a) showing the original stereo signal, Fig. 6 (b) showing the mono signal, Fig. 6 (c) showing the L signal and Fig. 6 (d) showing the R signal, the "L signal It can be seen that the "R signals" are separated from each other.

FIG. 6 (e) is a diagram illustrating synthesis of each component after adjusting gain for a stereo component in the separated signal as described above.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a view showing an operation process of an audio device applied to a portable terminal according to an embodiment of the present invention;

2 is a block diagram showing the configuration of an audio device applied to a portable terminal according to an embodiment of the present invention;

3 is a flowchart illustrating a process for providing a stereo effect in a portable terminal according to the present invention;

4 is a flowchart illustrating a process of providing a stereo effect in a portable terminal according to an embodiment of the present invention;

5 is a diagram illustrating a component extracted from an input signal according to an embodiment of the present invention;

6 is a diagram illustrating an audio signal processing of components extracted from the audio device.

Claims (20)

An audio device for providing stereo effect in a portable terminal, A component extraction unit for extracting mono components and stereo components included in the audio signal; And a gain adjusting unit for calculating a signal ratio of the stereo component to the mono component and adjusting the stereo gain according to the signal ratio. The method of claim 1, The gain control unit, In the case of the earphone output mode, the stereo effect is adjusted by the stereo gain control, and in the speaker output mode, after applying a head related transfer function (HRTF; Head Related Transfer Function), the stereo gain is characterized by adjusting the stereo effect. Audio device. The method of claim 1, The component extraction unit, After calculating the phase difference and the gain according to the phase difference using phase information on the components of the audio signal according to the frequency conversion and the phase magnitude, the audio signal is included in the audio signal using the gain and the phase information. An audio device, characterized by extracting mono and stereo components. The method of claim 3, wherein The audio device for providing a stereo effect in the portable terminal, An audio device comprising performing a frequency conversion process on the input audio signal using Equation 12 below.

Here, x _i (n) represents the sample value of the input signal in the time domain of the i-th microphone, and X _i (k; m) represents the frequency domain transformed value. In addition, M is a frame size, and k and m represent a k th FFT point value and an m th frame, respectively. The method of claim 4, wherein The audio device for providing a stereo effect in the portable terminal, The phase information of the component of the audio signal is calculated using Equation 13 below, and the phase magnitude is calculated using Equation 14 below.

Here, X (k; m) means a value that performs the frequency conversion process.

Here, X (k; m) means a value that performs the frequency conversion process. The method of claim 5, The audio device for providing a stereo effect in the portable terminal, An audio device, wherein the phase difference is calculated using Equation 15 below.

Here, X (k; m) means a value that performs the frequency conversion process. The method of claim 2, The gain control unit, An audio device comprising calculating a gain of a mono component according to the phase difference by using Equation 16, and calculating a gain of a stereo component according to the phase difference by using Equation 17 below.

Here, α is a constant for adjusting the amount of change of application according to the phase difference, and θ (k; m) represents the phase difference.

Here, α is a constant for adjusting the amount of application variation according to the phase difference, and θ (k; m) represents a phase difference. The method of claim 1, The component extraction unit, Using Equation 18 below And extract the mono component.

Here, the G _mono (k; m) represents the gain of the mono components, the _{| X L (k; m)} | is "L / R" phase component size, the ∠X _L (k; m ) Represents phase information of the "L / R" component. The method of claim 8, The component extraction unit, And extracting the "R" component using Equation 19, and extracting the "L" component using Equation 20 below to extract the stereo component.

Here, G _stereo (k; m) represents a gain value for a stereo component, and | X _R (k; m) | is a phase size of the "R" component, and ∠X _R (k; m) is The phase information of the "R" component is shown.

Wherein X _L (k; m) represents the "L" component of the stereo component, and G _stereo (k; m) represents the gain value for the stereo component, and the | X _L (k; m) | Is the phase magnitude of the "L" component, and ∠X _L (k; m) represents the phase information of the "L" component. The method of claim 7, wherein The gain control unit, The "R" component signal ratio of the stereo component to the mono component is calculated using Equation 21 below, and the "L" component signal ratio of the stereo component to the mono component is represented using Equation 22 below. The audio device, characterized in that for calculating.

Here, X _R (k; m) represents the "R" component extracted from the input signal, and X _mono (k; m) represents the mono component extracted from the input signal.

Here, X _L (k; m) represents the "L" component extracted from the input signal, and X _mono (k; m) represents the mono component extracted from the input signal. In the method for providing a stereo effect in a portable terminal, Extracting mono and stereo components of the audio signal; Calculating a signal ratio of a stereo component to the mono component; And adjusting the stereo effect through the stereo gain according to the signal ratio to output the audio signal. The method of claim 11, The process of outputting the audio signal, In the earphone output mode, the process of adjusting the stereo effect by adjusting the stereo gain, And in the speaker output mode, after applying a head related transfer function (HRTF), adjusting a stereo effect by adjusting the stereo gain. The method of claim 11, Extracting a mono component and a stereo component included in the audio signal, Calculating a phase information and a phase magnitude of a component of the audio signal by frequency converting the input audio signal; Calculating a phase difference and a gain according to the phase difference using phase information and phase magnitude of the component of the signal; And extracting the mono component and the stereo component using the gain and the phase information. The method of claim 13, Frequency conversion for the input audio signal, Method characterized in that it is performed using the following equation (23).

Here, x _i (n) represents the sample value of the input signal in the time domain of the i-th microphone, and X _i (k; m) represents the frequency domain transformed value. In addition, M is a frame size, and k and m represent a k th FFT point value and an m th frame, respectively. The method of claim 13, The phase information of the component of the audio signal is calculated using Equation 24, and the phase magnitude is calculated using Equation 25.

Here, X (k; m) means a value that performs the frequency conversion process.

Here, X (k; m) means a value that performs the frequency conversion process. The method of claim 13, The phase difference is It is characterized by using the following formula (26).

Here, X (k; m) means a value that performs the frequency conversion process. The method of claim 13, The gain of the mono component according to the phase difference is calculated using Equation 27, and the gain of the stereo component according to the phase difference is calculated using Equation 28 below.

Here, α is a constant for adjusting the amount of application variation according to the phase difference, and θ (k; m) represents a phase difference.

Here, α is a constant for adjusting the amount of application variation according to the phase difference, and θ (k; m) represents a phase difference. The method of claim 13, The mono component is characterized in that the extraction using <Equation 29>.

Here, G _mono (k; m) represents a gain value for the mono component, and | X _L (k; m) | is the phase size of the "L / R" component, and ∠X _L (k; m ) Represents phase information of the "L / R" component. The method of claim 13, The stereo component, <R> component is extracted using <Equation 30>, and "L" component is extracted using <Equation 31>.

Here, the G _stereo (k; m) represents the gain of the stereo component, the _{| X R (k; m)} | is "R" phase component size, the ∠X _R (k; m) is The phase information of the "R" component is shown.

Wherein X _L (k; m) represents the "L" component of the stereo component, and G _stereo (k; m) represents the gain value for the stereo component, and the | X _L (k; m) | Is the phase magnitude of the "L" component, and ∠X _L (k; m) represents the phase information of the "L" component. The method of claim 13, The "R" component signal ratio of the stereo component to the mono component is calculated using Equation 32, and the "L" component signal ratio of the stereo component to the mono component is used using Equation 33 below. The method characterized in that the calculation.

Here, X _R (k; m) represents the "R" component extracted from the input signal, and X _mono (k; m) represents the mono component extracted from the input signal.

Here, X _L (k; m) represents the "L" component extracted from the input signal, and X _mono (k; m) represents the mono component extracted from the input signal.

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